On Mon, Sep 21, 2009 at 11:55:37AM +0300, Avi Kivity wrote:
> Wait for 2000 cycles after the IPI to allow the host to schedule out.
> Measures wake-from-idle overhead.
>
> Signed-off-by: Avi Kivity <[email protected]>
> ---
> kvm/user/test/x86/vmexit.c | 11 +++++++++++
> 1 files changed, 11 insertions(+), 0 deletions(-)
>
> diff --git a/kvm/user/test/x86/vmexit.c b/kvm/user/test/x86/vmexit.c
> index 29bb32a..5088dc9 100644
> --- a/kvm/user/test/x86/vmexit.c
> +++ b/kvm/user/test/x86/vmexit.c
> @@ -66,6 +66,16 @@ static void ipi(void)
> on_cpu(1, nop, 0);
> }
>
> +static void ipi_halt(void)
> +{
> + unsigned long long t;
> +
> + on_cpu(1, nop, 0);
> + t = rdtsc() + 2000;
> + while (rdtsc() < t)
> + ;
I don't get the 2000 cycle thing. Since vcpu1 is on hlt by default, just
IPI'ing it to do nop() already includes wake-from-idle overhead?
Other than this the remaining is very nice, please apply.
> +}
> +
> static struct test {
> void (*func)(void);
> const char *name;
> @@ -76,6 +86,7 @@ static struct test {
> { mov_from_cr8, "mov_from_cr8" },
> { mov_to_cr8, "mov_to_cr8" },
> { ipi, "ipi", is_smp },
> + { ipi_halt, "ipi+halt", is_smp },
> };
>
> static void do_test(struct test *test)
> --
> 1.6.4.1
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